In co pending U.S. patent applications Ser. Nos. 606,785 (now abandoned), 606,786 (now abandoned), and 606,787 now U.S. Pat. No. 4,632,908, the disclosure of which are incorporated herein by reference, and in an article by Schultz et al., Two-Dimensional Centrifugation for Desk-Top Clinical Chemistry, Clin. Chem., Vol. 31, No. 9, pp 1457-63, (1985), an analytical cartridge centrifuge for bioanalysis of biological samples such as blood serum, plasma, spinal fluid and the like is described. One of the requirements for the successful operation of such an apparatus is that a test cartridge which is being revolved by a centrifuge to generate centrifugal force must be independently rotated approximately 90 degrees about its own axis to change the vector of the centrifugal force applied to its contents. In order perform this manuever there needs to be a separation in the second axis motor to allow for the rotation of the test cartridge on a shaft which is also revolving about the main centrifuge rotor (wheel) axis. Making this separation at the electrical level usually involves employing expensive slip rings having poor reliability and high maintenance requirements. Making this separation at the mechanical level involves mechanical linkages which add complexity and detract from overall reliability. The better solution and subject matter of the present invention is to separate a second axis induction motor between its stator pair and its induction rotor. At this point the energy transfer is via magnetic lines of force through air. Top reliability and great simplicity therefore can be obtained by separating the induction motor into two parts at this magnetic region where the one part can remain stationary while the other part can revolve with rotation of the main centrifuge wheel.